1. Field of the Invention
This invention relates to code multiplexing/reading apparatuses, and more particularly to a code multiplexing/reading apparatus adapted to multiplex on an video signal a code, for example, for distinguishing from which monitor camera a video signal is outputted or representing a time hour at which a video signal is outputted, as well as read that code out of the video signal multiplexed therewith.
2. Description of the Prior Art
There is shown in FIG. 8 and FIG. 9 one example of a conventional code multiplexing/reading apparatus of this kind. Referring to FIG. 8, during recordation a code stored by registers 2a-2g is multiplexed on respective predetermined two horizontal lines within a vertical blanking period contained in a composite video signal so that the code is thereafter recorded on a video tape (not shown) by a VTR3. During reproduction, the composite video signal is reproduced by the VTR3 as shown in FIG. 9, and then outputted through a drop-out detection circuit 3a. That is, where it is impossible to properly reproduce a signal due to damages or mars on a video tape, the signal is subjected to addition at its drop-out portion with using a signal corresponding to that of the preceding line, thereby being outputted. The two codes multiplexed on the composite video signal are detected through a comparator 4 and a code fetching circuit 5, and they are then compared by a comparing circuit 6. If they are coincident with each other, the first multiplexed code is outputted through a register 7.
When reproducing the composite video signal that is multiplexed with a code, e.g., xe2x80x9c1001101xe2x80x9d, even if a code first recorded is partly lost as shown in FIG. 10(A), the detected two codes will not coincide with each other as shown in FIG. 10(E) and FIG. 10(F). In this manner, an erroneous code, i.e. a code xe2x80x9c1000001xe2x80x9d is prevented from being outputted through the register 7.
In the prior art, however, if the first code is partly lost and further the next code be disappeared of its entirety as shown in FIG. 11(A), the first code with partly lacking is utilized for addition to a drop-out period in the latter half. In such a case, there happens coincidence between the two detected codes as shown in FIG. 11(E) and FIG. 11(F), resulting in outputting an erroneous code through the register 7.
It is therefore a primary object of the present invention to provide a code multiplexing/reading apparatus which is capable of preventing against outputting an erroneous code even when both of two codes are lost partly or in the entirety thereof.
It is another object of the present invention to provide a code reading device that can prevent against erroneously outputting a code therefrom even when both two codes are lost partly or in the entirety thereof.
It is further object of the present invention to provide a video reproducing device that can prevent against erroneously outputting a code therefrom even when both two codes are lost partly or in the entirety thereof.
It is still further object of the present invention to provide a video recording and reproducing apparatus that can prevent against erroneously outputting a code therefrom even when both two codes are lost partly or in the entirety thereof.
A code multiplexing/reading apparatus according to the present invention adapted to multiplex codes on a video signal to be recorded through a video record reproducing apparatus and read the code multiplexed on the video signal to be reproduced through the video recording and reproducing apparatus, comprises: a multiplexing means for multiplexing on a video signal two codes that are in a predetermined relationship; a code determining means for determining whether the two codes reproduced by the video reproducing apparatus are in the predetermined relationship or not; and a code output means for outputting a predetermined code when the two codes are determined that they are in the predetermined relationship by the determining means.
A code multiplexing/reading apparatus according to the present invention adapted to record a video signal multiplexed with codes on a recording medium by means of a signal recording means and reproduce the video signal multiplexed with the codes out of the recording medium by means of a signal reproducing means, comprises: a multiplexing means for multiplexing on a video signal two codes that are in a predetermined relationship: a code determining means for determining whether the two codes reproduced by the video reproducing apparatus are in the predetermined relationship or not; and a code output means for outputting a predetermined code when the two codes are determined that they are in a predetermined relationship by the determining means.
A code multiplexing/reading apparatus according to the present invention adapted to read a code that is multiplexed on a video signal to be reproduced by a video reproducing apparatus, comprises: a code determining means for determining whether two codes reproduced by the video reproducing apparatus are in a predetermined relationship or not; and a code output means for outputting a predetermined code when the two codes are determined that they are in the predetermined relationship by the determining means.
A code multiplexing/reading apparatus according to the present invention adapted to reproduced a video signal multiplexed with codes out of a recording medium by means of a signal reproducing means, comprises: a code determining means for determining whether two codes multiplexed on the video signal are in a predetermined relationship or not; and a code output means for outputting the predetermined code when the two codes are determined that they are in the predetermined relationship by the determining means.
The two codes that reside in a predetermined relationship are multiplexed during a vertical blanking period of the video signal by the multiplexing means. Here, the two codes involve for example a first code that is not inverted and a second code that is inverted in bit partly or in the entirety thereof. The video signal multiplexed with these two codes is recorded on the recording medium by means of the signal record means. The video signal multiplexed with codes is reproduced out of the recording medium by the signal reproducing means and determined by the code determining means whether the two codes involved are in the predetermined relationship or not. That is, the first code is stored by a storing means, the second code is inverted in bit partly or the entirety thereof, and an output of the storing means and an output of the inverting means are compared each other by a comparing means. If the two codes are determined that they are in the predetermined relationship, that is, these codes are determined coincident with each other, the code output means outputs a predetermined code. Here, the predetermined code refers, for example, to the first code.
In accordance with the present invention, since a predetermined code is outputted by the code output means only when the two reproduced codes reside in a predetermined relationship. Therefore, it is possible to prevent against outputting an erroneous code even when both two codes are lost partly or in the entirety thereof.
The above described objects and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.